81 Fiat Spider hot start problem

[joehorner]

I searched all the posts that dealt with hot starting problems, but I didn't see it solved. If there helpful posts on this topic please let me know.
I have been restoring a 81 spider 2000 for about a year. It sat for over a year before I bought it from the PO. I runs great when cold and drives great throughout the RPM range. It will not start when hot. It turns over great (especially after I put in the new reduction starter). It will barely start if it's under 180F. It will barely start when hot if I fool it by taking off the temp sensor at the T, but runs like crap unit I plug it back in. This temp sensor has been replaced twice. Get my parts from Csaba, so I know it's good. Here is what I have done:

New Cap, rotor, points, condenser, wires, plugs. (PO put a 72' dizzy on it). Checked and cleaned my grounds. New fuel filter, checked the fuel pump. (runs good) I get 32 psi on the fuel rail, which I cleaned. I cleaned the injectors. New fuel regulator. Ohms on throttle switch are correct. Ohms on cold start valve are correct. Auxilary air switch is closed when hot. Good O2 sensor. Timing checked. AFM door does not rub. I can hear the fuel pump run when manually opening the AFM door.

Getting spark when hot. I can push start it and it runs fine. It gets kind of hot in Houston mid-day, so I don't like doing that. If I wait for about 45 minutes after running it hot, it will start. By hot I mean over 190F. I have taken it to two mechanics in desperation. Now it runs much better with all the new parts I threw at it...but won't start when hot.

I have a couple things I hold suspect; Coil? AFM? I am really just grasping for things to think of. I would appreciate any help you can give.

[majicwrench]

Just making sure I understand.........you can push start it hot and it starts fine??? But will not start when being cranked by starter??
Keith

[WYSpider]

<deleted>

[vandor]

Two things I would try:
-try pushing on the gas pedal when trying to start it
-disconnect the blue cold start injector connector - if the Thermo Time Switch is bad the CSI can flood a warm engine

[joehorner]

Just making sure I understand.........you can push start it hot and it starts fine??? But will not start when being cranked by starter??
Keith

Yes, I can push start it hot and it starts fine but will not when cranking by starter.

[vandor]

>Yes, I can push start it hot and it starts fine but will not when cranking by starter.

Hm, I wonder it there is a bad electrical connection somewhere and the ignition or FI are not getting enough power when cranking.
You can try to install a Noid light on one of the injector's electrical connectors and see if it flashes when you are cranking.

It seems weird that it starts if you disconnect the coolant temp sensor, as disconnecting it makes the mixture rich. So you'd think it's not getting enough fuel otherwise.

[RRoller123]

Regarding the noid light on the injector lines, is it the case that they all 4 fire simultaneously?

[divace73]

my bet is it is the ignition switch.....It is worth cleaning out the switch and doing the brown wire fix and bypass the power sucking component (like head lights) with relays..just my 2.2c worth(GST Included in in Oz otherwise it would be 2c)

[majicwrench]

Should be pretty straightforward to see what is lacking when cranking it. If it won't start something is missing. I'd hook up fuel pressure gauge first. Then stick a noid in an injector connector. Go rrom there. And find a different mechanic.
' Keith

[joehorner]

Thanks for the help. I am going with a couple ideas right now. As Csaba suggested, I disconnected the cold start injector (blue) when hot, and it started better yesterday. I tried this a while back and it didn't make a difference, but that was before I changed the fuel filter out. The one that was on it (from PO) looked new but was filled with grit. (I know... I might have a fuel tank issue to deal with in the future) As for the ignition, I have already done the brown wire fix and starts great when not hot. Mark Allison made this comment when I sent him a PM:

Joe
the next step should be to see if the fuel system is holding pressure when you shut it off. If the pressure drops to zero, the fuel in the rail will boil when the engine is hot. If it's not holding pressure, it could be an injector leak, cold start injector leak, leaking check valve in the pump or leaking pressure regulator. Mark.

I will see if the fuel pressure stays up after I shut the car down. For others who might be trying to deal with this same issue, I am connecting a compression tester to the hose that goes to the cold start injector to test the fuel psi.

This problem seems more prevalent after a long drive then just gettting the fan to turn on twice in my driveway. I haven't figured out why unplugging the coolant sensor helps, but it does. Like you said, it would make it run rich. Will try to do some things you guys suggested and get back to you.

[majicwrench]

Unpluggin the coolant sensor PROBABLY helps cause you are having some sort of fuel delivery issue. By unpluggin sensor it is gonna open injectors wide when you try to start it. If you had a normal amount of fuel in lines, it would flood horribly and not start. If you do not have a normal amount of fuel, openin inj wide allows enough fuel in to get er running.
All this is just theory. You really need to test some things.
' Keith

[So Cal Mark]

somehow I missed the fact it will push start but not start when cranking. Is the cranking speed normal when hot? If you push start it, does it run poorly for a few seconds or does it start and purr immediately?

[joehorner]

somehow I missed the fact it will push start but not start when cranking. Is the cranking speed normal when hot? If you push start it, does it run poorly for a few seconds or does it start and purr immediately?

The cranking speed is normal when hot. I just installed a new starter recently and it works great hot and cold. After jump starting it, the car runs great right away unless I flooded it in the process of trying to start it. If so, it takes a couple pushes to clear the flood. It will only start when hot if I don't give it gas. Confusing.

Update on things I did today. Disconnected the cold start injector. The good news is that it will start when hot after about 15 seconds of turning it over. The bad news is it takes 15 seconds of turning it over on my starter. Better than pushing but not the fix I was hoping for. I also checked the fuel psi on the fuel rail. It is about 27psi when running and does not go down once the engine is off. I realize that there might be more than one problem here.

[majicwrench]

OK, back up, you have to jump start it??
' Keith

[joehorner]

OK, back up, you have to jump start it??
' Keith

Sorry if I was not clear. It starts great with the starter when cold and warm, but not hot. When hot the engine will turn over forever but not start. If I push start it, it will take off and run great. Disconnecting the cold start injector has enabled me to start it when hot after running the starter for about 15 seconds.

Unpluggin the coolant sensor PROBABLY helps cause you are having some sort of fuel delivery issue. By unpluggin sensor it is gonna open injectors wide when you try to start it. If you had a normal amount of fuel in lines, it would flood horribly and not start. If you do not have a normal amount of fuel, openin inj wide allows enough fuel in to get er running.
All this is just theory. You really need to test some things.
' Keith

What things would you have me test?